Exotensioned structural members with energy-absorbing effects

ABSTRACT

Structural members having enhanced load bearing capacity per unit mass include a skeleton structure formed from strips of material. Notches may be placed on the strips and a weave of tensile material placed in the notches and woven around the skeleton structure. At least one pair of structural members can be jointed together to provide very strong joints due to a weave patterns of tensile material, such as Kevlar, that distributes stress throughout the structure, preventing stress from concentrating in one area. Methods of manufacturing such structural members include molding material into skeletons of desired cross section using a matrix of molding segments. Total catastrophic failures in composite materials are substantially avoided and the strength to weight ratio of structures can be increased.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C §119(e) of U.S.provisional patent application No. 61/449,485 entitled “EXOTENSIONEDSTRUCTURAL MEMBERS WITH ENERGY-ABSORBING EFFECTS”, which was filed onMar. 4, 2011, the disclosure of which is incorporated herein byreference in its entirety.

STATEMENT REGARDING FEDERAL RIGHTS

This invention was made with government support under Contract No.DE-AC52-06NA25396, awarded by the U.S. Department of Energy. Thegovernment has certain rights in the invention.

TECHNICAL FIELD

Embodiments relate to structural members, and more particularly but notexclusively, to three-dimensional structural members having enhancedload bearing capacity per unit mass. Embodiments also relate to jointsand fasteners for the three-dimensional structural members. Embodimentsfurther relate to methods of manufacturing the three-dimensionalstructural members.

BACKGROUND

The pursuit of efficient structures in the civil, mechanical, andaerospace arenas is an ongoing quest. An efficient truss structure isone that has a high strength to weight ratio and/or a high stiffness toweight ratio. An efficient truss structure can also be described as onethat is relatively inexpensive, easy to fabricate and assemble, and doesnot waste material.

Trusses are typically stationary, fully constrained structures designedto support loads. They consist of straight members connected to jointsat the end of each member. The members are two-force members with forcesdirected along the member. Two-force members can only produce axialforces such as tension and compression forces about a fulcrum in themember. Trusses are often used in the construction of bridges andbuildings. Trusses are designed to carry loads which act in the plane ofthe truss. Therefore, trusses are often treated, and analyzed, astwo-dimensional structures. The simplest two-dimensional truss consistsof three members joined at their ends to form a triangle. Byconsecutively adding two members to the simple structure and a newjoint, larger structures may be obtained.

The simplest three-dimensional truss consists of six members joined attheir ends to form a tetrahedron. By consecutively adding three membersto the tetrahedron and a new joint, larger structures may be obtained.This three dimensional structure is known as a space truss.

Frames, as opposed to trusses, are also typically stationary, fullyconstrained structures, but have at least one multi-force member with aforce that is not directed along the member. Machines are structurescontaining moving parts and are designed to transmit and modify forces.Machines, like frames, contain at least one multi-force member. Amulti-force member can produce not only tension and compression forces,but shear and bending as well.

Traditional structural designs have been limited to one ortwo-dimensional analyses resisting a single load type. For example,I-beams are optimized to resist bending and tubes are optimized toresist torsion. Limiting the design analysis to two dimensionssimplifies the design process but neglects combined loading.Three-dimensional analysis is difficult because of the difficulty inconceptualizing and calculating three-dimensional loads and structures.In reality, many structures must be able to resist multiple loadings.Computers are now being utilized to model more complex structures.

Advanced composite structures have been used in many types ofapplications in the last 20 years. A typical advanced composite consistsof a matrix reinforced with continuous high-strength, high-stiffnessoriented fibers. The fibers can be oriented so as to obtain advantageousstrengths and stiffness in desired directions and planes. A properlydesigned composite structure has several advantages over similar metalstructures. The composite may have significantly higherstrength-to-weight and stiffness-to-weight ratios, thus resulting inlighter structures. Methods of fabrication, such as filament winding,have been used to create a structure, such as a tank or column muchfaster than one could be fabricated from metal. A composite cantypically replace several metal components due to advantages inmanufacturing flexibility.

There is a need to develop one or more structural members and structurestherefrom having enhanced load bearing capacity per unit mass, whichresist buckling and absorbs energy.

SUMMARY

According to one aspect, there is provided an energy-absorbingstructural member having an enhanced load bearing capacity per unitmass. The structural member comprises: strips of a material formed intoa skeleton of desired shape; spaced notches placed on side of the stripsof material; and a tensile material which is woven around the skeletonin a desired weave and placed in the notches.

According to another aspect, there is provided an energy-absorbingstructural member having an enhanced load bearing capacity per unitmass. The structural member comprises an elongated skeleton structurecomprising a plurality of strips of material; wherein the plurality ofstrips are joined together lengthwise along or around a common centralaxis of the skeleton structure and have long distal edges spaced apartabout the common central axis; and spaced notches placed on the stripsof material for anchoring tensile material to be woven around theskeleton structure in a desired weave.

According to yet another aspect, there is provided a jointed structure.The jointed structure comprises at least two adjoining energy-absorbingstructural members having an enhanced load bearing capacity per unitmass, wherein each of the structural members comprises: an elongatedskeleton structure comprising a plurality of strips of material; whereinthe plurality of strips are joined together lengthwise along or around acommon central axis of the skeleton structure, and wherein lengthwisedistal edges of the plurality of strips are spaced apart about thecommon central axis; spaced notches placed on the strips of material;and a tensile material which is woven around the skeleton structure in adesired weave and placed in the notches; and at least one jointcomponent joining the structural members together.

According to yet another aspect, there is provided a method ofmanufacturing an energy-absorbing structural member having an enhancedload bearing capacity per unit mass. The method comprises forming stripsof material into a skeleton structure of desired shape; placing notcheson the side of the strips; placing a tensile material in the notches;and weaving the tensile material around the skeleton in desired weave.

According to yet another aspect, there is provided a kit of parts forassembling a jointed structure. The kit of parts comprises a pair of theaforementioned energy-absorbing structural members and at least onecompression resistant member for fixedly seating in and joiningsubstantially aligned grooves of joining ends of a pair of the elongatedskeleton structures, wherein the elongated skeleton structure ends havecomplementary profiles and wherein each groove is formed by adjacentstrips of each skeleton structure end; and tensile material for weavingor whipping around adjoining ends of the skeleton structures; wherein,on assembly, the elongated skeleton structure ends are jointed togetherby the at least one compression resistant member and the tensilematerial weave at a desired joint angle.

According to yet another aspect, there is provided a kit of parts forassembling a jointed structure, the kit of parts comprising a pair ofthe aforementioned energy-absorbing structural members; at least oneprofiled connecting plate for covering joining long sides of thestructural members together; and a plurality of fasteners for fasteningthe connecting plate to the adjoining member long sides; wherein, onassembly, the structural members are jointed together by the fastenersfastening the at least one connecting plate to adjoining structuralmember sides.

According to yet another aspect, there is provided a method of jointingat least two structural members together. The method comprisingproviding a pair of the aforementioned energy-absorbing structuralmembers having an enhanced load bearing capacity per unit mass andjoining the pair of structural members together using at least onejointing component.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a structural member before it experiencesany loading;

FIGS. 2A-C show various embodiments of a structural member havingendured a skeletal failure, yet retained in close proximity by the weaveand core;

FIGS. 3A-C show various embodiments of a structural member after a corefailure;

FIG. 4 shows a cross-sectional view of an embodiment of a structuralmember;

FIGS. 5A-B are close-up side views of an embodiment of a structural;member which show the notch detail and binding agent used to adhereweave to skeleton;

FIG. 6 shows the results of tests done on a carbon fiber composite solidtube;

FIG. 7 shows the results of tests done on one embodiment of a Brockwellstructure. Unwoven samples visually demonstrate the multinodal mode ofenergy absorption via sine wave-like shape in areas of compression;

FIG. 8 shows the results of tests done on an embodiment of thestructure;

FIGS. 9A-9D show additional test results comparing a tube with thedifferent embodiments of the structure;

FIGS. 10A-10D show summaries of selected mechanical parameters for tubesand different embodiments of the structure;

FIG. 11 shows a perspective end view of part of an exemplary structuralmember showing an embedded central core, skeleton structure, and weaveplaced in notches according to one embodiment;

FIG. 12 is a partial side view of an exemplary structural memberaccording to another embodiment in which strands extend along the stripdistal edges for resisting notch failure propagation.

FIG. 13 is a perspective view of an exemplary structural memberaccording to yet another embodiment;

FIG. 14 is a partial perspective end view of an exemplary structuralmember according to yet another embodiment;

FIGS. 15 A to 15 E illustrate different stages of construction of anexemplary permanent jointed connection of structural members accordingto one embodiment;

FIGS. 15 F to 15 G illustrate different stages of construction of anexemplary lateral quick jointed connection of structural membersaccording to another embodiment;

FIG. 16 A illustrates a perspective top view of an exemplary lateralslide joint slidably mounted on the exterior of a structural memberaccording to one embodiment;

FIG. 16 B illustrates a perspective rear view of the exemplary lateralslide joint of FIG. 16 A;

FIG. 17A illustrates a cross sectional view of an exemplary mold in aclosed configuration for molding a skeleton structure according to oneembodiment;

FIG. 17B illustrates a cross sectional view of the mold of FIG. 17A inan open configuration according to one embodiment;

FIG. 17C illustrates a cross sectional view of the mold indicating howmolding segments in the open configuration shown in FIG. 17 B arepressed together according to one embodiment;

FIG. 17D illustrates a cross sectional view of the mold in an openconfiguration in which molding segments are moved outwardly from themolding configuration shown in FIG. 17C to release the formed skeletonstructure; and

FIGS. 18A to 18D illustrate different stages of construction of anexemplary T joint connection of structural members according to oneembodiment.

LIST OF REFERENCE NUMERALS

-   -   1. Central Core    -   2. Skeleton    -   3. Notch    -   4. Tensioned Weave    -   5. Longitudinal Strand    -   6. Spacing between notches    -   7. Removal of Skeletal material/mass    -   8. High-Density/fire retardant Foam Filler    -   9. Shrink-Wrap or other exterior coating applied    -   10. Protective Skeletal Skin    -   11. Compromised Skeletal member    -   12. Binding Agent (CA or other adhesive)    -   13. Multinodal mode of energy absorption. Shifts to higher        frequency in weaved samples.    -   14. Compression Resistant Resin Joint Member    -   15. Embedded Spar within shaped joint    -   16. Lateral reinforcing spars (×2)    -   17. Tension resistant lashing    -   18. Mold Cross-Section    -   19. Quick-Joint Lateral Plate/Dissimilar Material    -   20. Weave-captured V-Nut and bolt for fastening    -   21. V-slot linear slide joint    -   22. Teflon friction-resistant jacket    -   23. U-frame for V-slot slide joint    -   24. Tethered cinching effect on skeleton    -   25. Carbon-Fiber or other    -   26. Kevlar or other    -   27. Zylon or other    -   28. Skeletal coating, aluminized mylar or other    -   29. Jointing plate    -   30. V-profile captured nut    -   31. Fastening Bolt    -   32. Insertion of captured nut into weave    -   33. Complementary cut for skeletal intersection    -   34. Exposed Skeletal V-Profile    -   35. Distal Skeletal Edge    -   36. Strips of Material

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particularembodiments, procedures, techniques, etc. in order to provide a thoroughunderstanding of the present invention. However, it will be apparent toone skilled in the art that the present invention may be practiced inother embodiments that depart from these specific details.

Technical features described in this application can be used toconstruct various embodiments of energy-absorbing structural members,also referred to hereinafter as “Brockwell Structures”.

In one approach, an energy-absorbing structural member having anenhanced load bearing capacity per unit mass has strips of materialformed into a skeleton of desired shape. Spaced notches are placed onside of the strips of material. A tensile material is woven around theskeleton in a desired weave and placed in the notches.

By providing spaced notches on the side of the strips of material and atensile material which is woven around the skeleton structure in adesired weave, the structure resists buckling and absorbs energy.Lightweight and high strength structures can be provided with theability to avoid catastrophic failure.

The angle of the weave can vary between 0° and 180°.

In another example, an energy-absorbing structural member having anenhanced load bearing capacity per unit mass has an elongated skeletonstructure comprising a plurality of strips of material. The plurality ofstrips are joined together lengthwise along or around a common centralaxis of the skeleton structure and have long distal edges spaced apartabout the common central axis. Spaced notches are placed on the stripsof material for anchoring tensile material to be woven around theskeleton structure in a desired weave. Weave placed in the notches canbe recessed flush with, or within, strip distal edges. For example, thestructural member can include an embedded central core of material whichis tensioned or flaccid. The structural member can include an elongatedpassageway for carrying hydraulic, pneumatic and/or electricalcomponents therein. A high density fire resistant foam filler can beinserted between the strips,

In yet another approach, a jointed structure comprises at least two ofthe structural members of one or more embodiments joined together by oneor more joint components of one or more embodiments described herein.For example, in one approach, a jointed structure has at least twoadjoining energy-absorbing structural members having an enhanced loadbearing capacity per unit mass. Each of the structural memberscomprises: an elongated skeleton structure comprising a plurality ofstrips of material; wherein the plurality of strips are joined togetherlengthwise along or around a common central axis of the skeletonstructure, and wherein lengthwise distal edges of the plurality ofstrips are spaced apart about the common central axis; spaced notchesplaced on the strips of material; and a tensile material which is wovenaround the skeleton structure in a desired weave and placed in thenotches. The jointed structure has at least one joint component joiningthe structural members together.

The at least one joint component can comprise at least onecompression/tension resistant member fastening adjoining portions of theskeleton structures together. At least one joint component can forexample comprises tensile material woven or whipped around adjoiningportions of the skeleton structures. The tensile material can be wovenor whipped around the adjoining portions is set in a resin. In oneexample, an end of one of the elongated skeleton structures is joined toan end of the other of the elongated skeleton structures, wherein thejoined skeleton structure ends have complementary profiles and whereinat least one groove formed by adjacent strips of one joined skeletonstructure end is substantially aligned with at least one groove formedby adjacent strips of the other joined skeleton structure end.

The at least one joint component can comprise a compression resistantmember fixedly seated in and joining the substantially aligned groovestogether. The compression resistant resin member can be set in at leastone inside corner formed by the skeleton structure end grooves joiningtogether. In another example, the at least one jointing component cancomprise a profiled connecting plate covering at least a pair ofadjoining member long sides and a plurality of fasteners fastening theconnecting plate to the adjoining member long sides. The fasteners cancomprise first fastener components mating corresponding second fastenercomponents, the second fastener components being retained in groovesformed between adjacent strips on each of the adjoining member longsides. The second fastener components and the grooves can havecomplementary profiles, wherein the second fasteners are retained seatedin the grooves by the weave covering the grooves and wherein the platecovers the weave. For example, each first fastener can comprise athreaded screw or bolt, wherein each second fastener comprises acorresponding threaded nut, and wherein each screw or bolt is receivedin a respective through hole formed in the plate and screwed or boltedto the corresponding threaded nut captured in the groove by the weavesuch that the plate connects the skeleton structure long sides together.The grooves can be V-profiled grooves, wherein the nuts are V-profilednuts, and wherein the V-profiled nuts fit into the grooves such that thenuts are prevented from rotating in the V grooves. The connecting platecan be releasably fastened to the long sides by the fasteners. Theconnecting plate and the adjoining long sides can be substantiallycoplanar.

-   In yet another approach, a method of manufacturing an    energy-absorbing structural member having an enhanced load bearing    capacity per unit mass is provided in which strips of material are    formed into a skeleton structure of desired shape. Notches are    placed on the side of the strips. Tensile material is placed in the    notches and woven around the skeleton in a desired weave.-   In one example, the method includes feeding lengths of material into    an open mold having a plurality of elongated mould segments arranged    lengthwise side by side in a matrix and spaced apart from one    another around a central common axis; moving the plurality of    elongated segments inwardly together towards the central common axis    to shape the material into strips joined together lengthwise along    or around the common central axis with long distal edges of the    strips spaced apart about the common central axis; curing the    material; moving apart the plurality of elongated segments to open    the mold; removing the skeleton member from the open mold. Feeding    lengths of material can comprise for each mold segment, providing    associated elongated layers of fiber material having cross sections    complimenting profiles of a molding surface of the molding segment;    and nesting together lengthwise sets of the associated elongated    layers inside the mold in alignment with the respective mold segment    molding surfaces. In one example, the elongated mold segments have    an L shaped inner profile surface and are arranged longitudinally in    a 2×2 matrix; wherein the elongated layers have L shaped cross    sections; and wherein the skeleton of desired shape has a + cross    section. The fiber material can comprise pre-impregnated carbon    fiber.

The method can further comprise placing strands of tensile material inthe open mold adjacent nested layers of material and in alignment withcomplementary grooves formed in the mold segments.

-   In yet another approach, a kit of parts for assembling a jointed    structure is provided. The kit of parts comprises a pair of    energy-absorbing structural member having an enhanced load bearing    capacity per unit mass, each structural members comprising an    elongated skeleton structure comprising a plurality of strips of    material; wherein the plurality of strips are joined together    lengthwise along or around a common central axis of the skeleton    structure and have long distal edges spaced apart about the common    central axis; and spaced notches placed on the strips of material,    and tensile material which is woven around the skeleton structure in    a desired weave and placed in the notches; a least one compression    resistant member for fixedly seating in and joining substantially    aligned grooves of joining ends of a pair of the elongated skeleton    structures, wherein the elongated skeleton structure ends have    complementary profiles and wherein each groove is formed by adjacent    strips of each skeleton structure end; and tensile material for    weaving or whipping around adjoining ends of the skeleton    structures; wherein, on assembly, the elongated skeleton structure    ends are jointed together by the at least one compression resistant    member and the tensile material weave at a desired joint angle.    -   The kit of parts can further comprise compression resistant        resin for setting the at least one compression resistant member        inside a corner formed by the skeleton structure end grooves        joining together.

In yet another approach, kits of parts are provided for assembly of thejointed structures of embodiments described herein. For example, in oneapproach, a kit of parts for assembling a jointed structure is provided.The kit of parts comprises a pair of energy-absorbing structural membershaving an enhanced load bearing capacity per unit mass, each structuralmember comprising an elongated skeleton structure comprising a pluralityof strips of material; wherein the plurality of strips are joinedtogether lengthwise along or around a common central axis of theskeleton structure and have long distal edges spaced apart about thecommon central axis; spaced notches placed on the strips of material,and tensile material which is woven around the skeleton structure in adesired weave and placed in the notches; at least one profiledconnecting plate for covering joining long sides of the structuralmembers together; and a plurality of fasteners for fastening theconnecting plate to the adjoining member long sides. wherein, onassembly, the structural members are jointed together by the fastenersfastening the at least one connecting plate to adjoining structuralmember sides.

In yet another approach, a method of jointing at least two structuralmembers together comprise: providing a pair of energy-absorbingstructural member having an enhanced load bearing capacity per unitmass, each structural member comprising an elongated skeleton structurecomprising a plurality of strips of material; wherein the plurality ofstrips are joined together lengthwise along or around a common centralaxis of the skeleton structure and have long distal edges spaced apartabout the common central axis; and spaced notches placed on the stripsof material; and tensile material which is woven around the skeletonstructure in a desired weave and placed in the notches; and joining thepair of structural members together using at least one jointingcomponent.

In yet another approach, kits of parts are provided for assembly of thestructural members of embodiments described herein.

In one approach, one or more of the aforementioned kits of parts areprovided in a box together with instructions carried on a suitable mediafor instructing a user on how to assemble the parts.

Reference will now be made to the drawings in which the various elementsof embodiments will be given numerical designations and in whichembodiments will be discussed so as to enable one skilled in the art tomake and use the invention.

Specific reference to components, process steps, and other elements arenot intended to be limiting. Further, it is understood that like partsbear the same reference numerals, when referring to alternate Figures.It will be further noted that the Figures are schematic and provided forguidance to the skilled reader and are not necessarily drawn to scale.Rather, the various drawing scales, aspect ratios, and numbers ofcomponents shown in the Figures may be purposely distorted to makecertain features or relationships easier to understand.

FIGS. 1 to 5B of the accompanying drawings depict an embodiment of theBrockwell structure. The structural member has an elongated skeletonstructure 2 comprising a plurality of strips 36 of material. In thefigures, the elongated skeleton structure is a straight length memberbut in other examples, the elongated skeleton structure may be a curvedlength member or even a ring shaped member. The plurality of strips 36are joined together lengthwise along or around a common central axis andhave long distal edges 35 spaced apart about the common central axis.Each strip is a planar strip that has circular cut outs but in otherembodiments one or more strips may have other profiles with or withoutcut outs.

In the example FIGS. 1 to 5B, the structural member has 4 planar strips36 that are spaced apart equally such that the skeleton structure hasa + cross section. The number of strips and/or skeleton structure crosssection may be different in other embodiments. By way of example, themember may have 3 planar strips arranged to form a skeleton structurewith a Y shaped cross section or 2, 3 or 4 strips etc. arranged to forma skeleton structure with a T shaped cross section.

Spaced notches 3 are placed on the strips 36 of material. As best shownin FIGS. 5A and 5B, notches 3 are spaced along strip distal edges 35. Inother embodiments, the notches may be placed in other positions in thestrips. Notches 3 serve as anchor points for tensile material 4 which isplaced in the notches and woven around the skeleton structure in adesired weave. The weave is pre-tensioned and recessed flush with, orwithin the strip distal edges 35. However, in other embodiments, theweave may protrude beyond the distal edges and need not bepre-tensioned. In the example of the structural members illustrated inFIGS. 1-5B, a central core 1 of failure propagation resistant materialis embedded in skeleton structure 2 and extends along the common centralaxis. A failure propagation material 5 is also formed in the stripsextending longitudinally. A binding agent or other adhesive 12 adheresweave 4 to the notches 3. The binding agent 12 aids in preventing weave4 slippage and distributing stresses throughout the structural memberbeam via the other anchor points and the central core 1. In anotherembodiment, the binding agent is omitted.

As will be explained in more detail below, the strip material and weavetensile material are selected to provide desired energy absorbing andload bearing capacity properties. In the example of FIGS. 1-5B, eachstrip of material is a rigid elastic material, in this particular case,resin pre-impregnated carbon fiber but other materials are envisagedsuch as but not limited to recyclable or non recyclable plastics orglass. The strips and resulting skeleton structure can be made from anymaterial that holds its shape with a load. Whilst strips of materialthat are capable of exhibiting both compression properties and tensionproperties are more beneficial for the structural member, in otherembodiments, materials that only exhibit compression or tension are alsoenvisaged.

Weave tensile material 4 is Kevlar but other tensile materials areenvisaged such as, for example Zylon. The binding agent 12 may be forexample cyanoacrylate glue, or epoxy. Centralcore 2 is made from Zylonbut alternative failure propagation resistant materials may be employed.Failure propagation resistant element 5 may also be Zylon or othertensile material. Central core 1 may be a tensioned or flaccid materialdepending on the desired properties of the structural member. In otherembodiments, central core 1 may be omitted.

The joints of carbon tubes and rods tend to be weak due to the use ofmechanical fixtures and glues. When materials break, they tend to do soin a violent manner, which causes separation and total failure of theseparts. As described herein, the structure of one embodiment is abuilding material made of both beams and fibers that are ultra-light andultra-strong per unit mass. Additionally they have the followingproperties:

-   -   Are lightweight    -   Have better energy absorption than tube structures    -   Normalized bending stiffness (rigidity) on par with tubes of        similar mass    -   Have higher buckling loads by restricting the buckle to occur at        higher frequency modes

A comparison of the Brockwell Structures to common building materials isshown in Table 1.

TABLE 1 Comparative materials Strength-to-weight ratio Failure modeBrockwell Structure High Ductile Steel Medium Ductile Aluminum MediumDuctile FRP High Brittle FRP as strengthening material Medium Brittle

The jointed structure according to one or more examples has very strongjoints due to a weave pattern of Kevlar that distributes stress throughthe joint from member to member, thus preventing stress fromconcentrating in one area. Notching along the edge of each member-sparprovides a static anchor point for the Kevlar weave. The innovativedesign and scalable manufacturing method of embodiments, mitigates totalcatastrophic failures in composite materials and increase the strengthto weight ratio of the structures.

The primary role of the external weave pattern is to distribute forcesthrough the structure and hold the graphite skeleton in place. Thisprevents bowing and keeps the structure in rigid stage. The secondaryrole of the external weave pattern is to sinch down on the graphite oncethe structure has been compromised and is in the process of being pulledapart. Sinching has a dampening effect that increases resistance as itis pulled. Also, the weave serves as a protective layer which guards theinternal skeleton from damage including direct impact, abrasion,cutting, etc. Finally, the third role of the Kevlar weave pattern is tokeep the broken structure tethered together and prevent a catastrophicfailure and separation.

In one example, the structure comprises a carbon fiber (FRP) structuralskeleton, tensioned Kevlar weave wrap, and internal tensioned or flaccidstrands of high-tensile material as the embedded core for fractureresistance. Additionally, pre-tensioned high-tensile mass may be appliedlongitudinally to the distal aspects of the member-spars, parallel tothe core, thus further inhibiting propagation of notch failure. Thestructure may also have a coating, such as a metal coating forresistance to ultraviolet degradation. The basic structure can bedesigned and assembled/constructed for each application based upon theapplication needs, for example optimization for specific forces themember needs to withstand, such as compression, tension, torsion,flexion, wear and tear, or any combination of the above.

FIGS. 1-3 show the structure of an embodiment during the three distinctbreaking phases. FIG. 1 shows the structure of an embodiment when it isin the strong phase, before sufficient load has been applied to causeany breakage.

In a total failure scenario the Brockwell Structure of one or moreembodiments passes through multiple distinct loading phases, the resultof a combination of different material properties and structuralfeatures. In the initial strong phase (FIG. 1), the skeletal strips 2are rigid and intact around the central core 1 and the weave 4 is firmlyattached to the notches 3.

As load increases, the structure exhibits ductile-like behavior (FIG.9A) as buckling 13 is initiated in compressed skeletal strips 2. Thefeature of the bound skeletal notch 3 and weave 4 restrict the buckling,increasing the number of buckles 13 along the structure, making it morerigid and stronger compared to the unwoven specimen FIG. 9A. This is aresult of distributing stress through the combination of core element 1,skeletal strips 2, and weave 4.

If the skeletal strips 2 are compromised, the structure transitions intoa constrained non-rigid close-proximity post rupture phase (FIG. 2 a-c).In this phase, the tension-resistant core element 1, longitudinalstrands 5, and weave 4 stay intact, constraining skeletal 2 damage toclose-proximity.

As failure propagates, and the longitudinal strands 5 and/or the centralcore 1 material fails, the structure enters an energy-absorbingelongating tether phase (FIG. 3 a-c). Tether elongation occurs throughseparation of the skeletal structure 2 under tension, reducing the anglebetween the weaves 4 at their crossing points. This reduces the radialdistance between opposing sides of the weave 4 and hence the overallcircumference, cinching in upon and crushing the skeleton 2, resultingin even more energy absorption before complete separation. The abovebreakdown phases enable the Brockwell Structure tolerant of load/strainthroughout each successive breakdown phase prior to total failure. Thiscombination of different material properties and structural featuresrenders the Brockwell Structure, complete with its jointing andfastening systems, a light, safe, and strong generic structural framingsystem.

FIG. 4 shows the Brockwell structure according to one example and itsthree key components: the carbon fiber skeleton 2, the Kevlar weave 4,and the central strands of Zylon 1. The optimization and integration ofthese three components provide great flexibility in the application ofthe Brockwell Structure, and render the Brockwell Structure a unique andinnovative building material that has the multiple benefits of achievinglight weight, high strength, and blast resistance. Moreover, the threekey components allow for a broad choice of design attributes in rawmaterials selection, structure unit design, and production for both thebasic spar and joint structures.

Wide selections of raw materials can be integrated and designed into theBrockwell Structure. For the most part, these raw materials arecommercially ready FRPs with proven performance. For example, variouscombinations of materials can be used in the Brockwell Structure moldingprocess for specific applications. Also, the Brockwell Structure can usea wide range of high tension materials such as Kevlar, Zylon, Spectrafiber, etc.

In one example, integration of the three components, skeleton, weave andcore, into one Brockwell Structure can be used to make basic spar andjoint structure units that can achieve optimized application-specificperformance, including requirements related to loading, strength,desired failure mode, and fatigue. The following features can bemanipulated in the design/integration of components to shift failuremodes:

-   -   Notch (weave) density    -   Weave tension/strength    -   Number of strands of weave    -   Weave pattern and angle    -   Number of strands inserted into the mold

The Brockwell Structure offers various choices of basic structure andjoint structure skeletons to meet application-specific needs, such asthe Y-beam, +-beam, X-beam, O-beam, etc. The shape, the size, thicknessand dimension of the mold can be optimized during theapplication-specific design process.

As described further below, Brockwell Structures of one or moreembodiments are lightweight and high strength, have an ability to avoidcatastrophic failure, and provide ease of manufacturing andinstallation. In addition, Brockwell Structures can (1) provide anintegral combination of compression and tension resisting capability;(2) tailor the stress distribution in the structural member; (3) enablethe prediction of the rupture location/zone based on the design; (4)provide a customized design based on the loading conditions andapplication requirements; and (5) provide an ability to engineer/designrupture in either tension or compression first.

Lightweight and High Strength: The Brockwell Structure of one or moreembodiments takes advantage of the fact that the FRP is a lightweighthigh-strength structural material, as well as using the weave to controlthe failure mode. Because the main raw material in Brockwell Structures,in one embodiment, is carbon fiber wrapped (weaved) with high-tensilematerials such as Kevlar and Zylon, building units made of BrockwellStructures of one or more embodiments can be designed to be rigid,lightweight, and more capable of withstanding significant stresses(compression, and tension, as compared with materials such as steel,carbon tubes, or FRP alone.

Ability to Avoid Catastrophic Failure: Brockwell Structures provide theenergy absorption needed to prevent catastrophic failure, therebyovercoming the brittle failure mode associated with current FRPcomponents. Brockwell Structures localize any failure, avoidcatastrophic failure and increase survivability while maintaining thelightweight and high-strength characteristics. Brockwell Structures ofone or more embodiments also have built-in properties of ductile failurebehavior provided by the skeletal buckling, as restricted by thetensioned weave.

Should the structural skeleton fracture, the external weave resistsseparation by remaining intact while constricting upon the inner mass(the strips) and absorbing massive tensional resistance in the process.Also, the built-in internal strands of high tensile material, such asKevlar or Zylon, which are introduced in the skeletal structure duringthe FRP molding process, make the skeleton harder to separate, and thusstay in close proximity to its failure location. These performancequalities have the potential to be harnessed as a safety mechanism (suchas the crumple zone) that can be engineered into structural members inhigh impact areas. For one or more embodiments, the blast resistance(from the fracture initiation to final separation and catastrophicfailure) increases by a factor of about 10-15 times the force whichinitiates skeletal fracture.

Ease of Manufacturing and Installation: Brockwell Structures can beeasily engineered into different application-specific shapes and formssuited to loading requirement, service, durability requirement, and thecost demand, while maintaining its lightweight, high-strength, andenergy absorption structural performance qualities. Brockwell Structurespossess the flexibility of being constructed as a lightweight framingmember in which abundant local material (such as dirt, rocks, clay, andwater) is used to fill structural voids as needed to enhance stabilityand add mass. Finally, Brockwell Structures possess the followingadvantages with respect to installation and maintenance:

-   -   They can be the stand-alone materials. Even though the Brockwell        Structure is the framing 3D member, longitudinal spars could be        used in a 2D surface, much like the divider inside of a wine box        but spiraled further in two dimensions.    -   They can be used as reinforcement or to supplement members of        concrete, metal bridges or other structures.    -   They have onsite repair capability due to the ease and        simplicity of assembly. One way to approach the repair is by        adding Brockwell Structure mass in an area in need of repair.        The additional strength in the repaired area would be analogous        to the calcified lump in a bone that has healed after fracture,        rendering the bone even stronger.    -   They can be assembled anywhere using a simple, versatile,        flexible molding and weaving process.

Reference will now be made to FIGS. 11-14, which depict yet furtherembodiments of structural members. FIG. 11 illustrates a perspectiveview of a structural member similar to that of FIGS. 1-5B but with nocut outs in strips 50 and without longitudinal strands 5. FIG. 12 is apartial side view of an exemplary structural member according to anotherembodiment again without cut outs but showing longitudinal strands 5placed proximate the notches. This is a strong-phase structure withadded mass (the strands). The longitudinal strand not only increasestensional strength, but also helps to prevent failure propagation fromthe notch.

FIG. 13 is a perspective view of an exemplary structural memberaccording to yet another embodiment in which strands extend lengthwiseproximate unnotched distal edges and strip cut outs 7 are provided.Strip cut outs 7 have different patterns. This illustrates variations inmass which may be implemented in the finished structure, including theelimination of mass from the skeleton 2, as well as the addition oflongitudinal strands 5, including but not limited to high-tensilematerial, or electrical wiring;

FIG. 14 is a partial perspective end view of an exemplary structuralmember according to yet another embodiment. This figure depicts aprotective skin 10 on the skeleton (for example but not limited toAluminized Mylar (28), in this instance), skeletal filler material 8(High density foam, in this case), and a sheathing material 9 to encasethe entire structure (such as shrink-wrap).

A method for manufacturing an energy-absorbing structural member havingan enhanced load bearing capacity per unit mass according to oneembodiment will now be described. This method may be used to manufacturestructural members of one or more of the embodiments shown in theaccompanying figures. As a general outline, the method begins withforming strips 36 of material into the skeleton structure 2 of desiredshape. Then, notches 3 are placed on the sides of the strips. Tensilematerial 4 is placed in the notches and woven around the skeleton in thedesired weave.

The process of forming strips of material into the skeleton structure ofdesired shape can be performed using a variety of techniques. In oneexample, the skeleton structures are compression molded employing a moldshaped to mold the material into the structural member skeletonstructure of desired cross section. In one example, the skeletonstructure is made from an extrudable material, such as metal, glass orplastic, which is extruded to form the skeleton structure of thestructural member. By way of example, pultrusion or other processesknown to the person of ordinary skill may be used to form the skeletonstructure 2. Such techniques also enable composite skeleton structuresto be formed including the central core 1 and longitudinal strands 5, asnecessary. For example, skeleton structures of carbon fiber can beextruded or pultruded by known methods. In other examples, injectionmolding techniques may be employed to form the skeleton structures fromthermoplastics and other types of injection moldable materials.

Once the skeleton structure is formed, in one example, a rotary cutter,or other notching device is then used to cut notches 3 into the lateraledges 35 of each strip at intervals. Under tension, a strand of Kevlaror other tensile material is then helically wound about the skeletonstructure 2 back and forth longitudinally, laid into the notching 3, toproduce a clockwise and counter-clockwise weave 4. Once woven, anadhesive 12 such as, cyanoacrylate, epoxy, or lacquer is then applied toeach weave/notch junction 3, binding the weave to the skeleton 2, andcompleting the construction of a Brockwell Structure.

The shape of the mold for molding the skeleton structure 2 will dependon the desired cross-section of the structure. The mold has a pluralityof elongated segments 18 which are placed lengthwise side by side withthe molding surface of one segment facing a corresponding moldingsurface of an adjacent segment. Each segment molding surface is profiledto provide the desired strip shape and desired cross section of theelongated skeleton structure. By way of example, an exemplary moldaccording to one embodiment for molding a skeleton structure with a +cross section is illustrated in cross-sectional views of FIGS. 17A-17D.The mold has four elongated molding segments having squarecross-sections and arranged longitudinally side by side in a 2×2 matrixfor forming a + cross-sectional skeleton structure at the centerjunction or common axis of the matrix. For molding Y shaped crosssection skeleton structures, the mold has three molding segments andthree for molding T shaped cross-sections.

The molding process starts by feeding lengths of the material, profiledto align with a respective molding segment surface, into the open moldand aligning fiber or other lengths of material with the segment moldingsurfaces. In the example of FIG. 17A-D, the fiber lengths are made ofpre-impregnated carbon fiber. However, as already explained above, otherdesired material may be used. For the + cross section mold shown in FIG.17B, the lengths of material fed into the mold have L cross-sectionsmatching the profile of respective molding segments. The L crosssectioned lengths of material are then layered in nested relation overthe 90 degree corner of each segment molding surface long axis. Ifdesired, Kevlar or Zylon thread or other failure propagation resistantmaterial may be inserted into the middle of the molds to form a centralcore 1 and/or inserted and aligned with longitudinal grooves in themolds for incorporating notch reinforcing tensile elements 5 into themolded strips.

Once the molds 18 have been compressed together as shown in FIG. 17C bya suitable compression tool or device (not shown) to mold the materialinto a + cross-section, the molds are heated to begin the curingprocess. For a carbon fiber skeleton structure, the skeleton structurecures at a temperature of about 285° Fahrenheit after about 45 minutesof heating. After cooling to room temperature, the molds are removed,leaving the +-shaped skeleton (2). Excess resin and flashing from themolding process may then be removed.

Preliminary Results

In experimental measurements, high quality carbon fiber epoxy compositecircular tubes were selected as the baseline structure, because thecircular tube is one of the most efficient structural elements widelyused in various applications. The initial investigation on limitedsamples showed that the basic Brockwell Structure surpasses the carbontubes with respect to lightweight and high-strength materialsperformance in the following ways (shown in FIGS. 6-9):

-   -   The Brockwell Structures had only ½ to ⅔ of the linear mass        density of carbon tubes.    -   At the first stage of failure, the Brockwell Structures absorbed        2 to 3 times more energy compared with the circular tubes, which        failed catastrophically in a brittle fashion.    -   The Brockwell Structures sustained a sequence of failures in a        gradual manner, rather than catastrophic failure manifested by        total separation.    -   Weaved samples sustained at least twice as much buckling load.    -   The Brockwell Structures had a normalized bending stiffness        (rigidity) that was similar to circular tubes with similar mass.        Additionally, preliminary results suggest that the force        required to bring the structural member to separation is 10 to        15 times the force at the initial fracture. This is made        possible by some of the following unique design features:    -   Weaving: Another mechanism built into Brockwell Structure can        prevent sudden failure—the weave, initially designed to increase        rigidity, it also can hold fractured internal skeletal members        in close proximity. As greater force is applied after the        internal skeletal member starts to crush, the external        counter-woven member remains constricted in a tethered fashion,        thereby holding the structure in place. This action yields        progressively increasing tensile strength while resisting        separation and absorbing massive amounts of energy in the        process.    -   Groove Notch Design: FIG. 4 shows a close-up of a tensioned        weave inside notches on a skeletal member. The notches represent        a new design feature that enables the structure to hold together        when it has been broken elsewhere. By adding notches along the        edges of the core structure, the new Brockwell Structure design        enables the weave component to remain with the skeleton member        and prevent sliding. Because the weaves in the neighborhood of        the failure are intact, they, in turn, prevent the failure from        propagating further, or slow down the failure process.    -   Structural Design: Both (1) the Brockwell Structure member,        and (2) the Brockwell Structure joint can be designed,        engineered, and assembled/constructed into structural members to        meet the needs of specific applications. For example, Brockwell        Structures can be designed and constructed to optimize for the        type of stress each structural member might need to withstand        under given loading conditions: compression, tension, torsion,        or wear/tear resistance (such as for example in bridge deck        application).    -   With respect to combating compression forces, the simplest        method would be to add mass in the area where buckling would        likely occur. An example would be to add mass to an area under        compression/tension. However, more complex solutions can be        engineered—e.g., a 0-90 degree pattern of woven fibers could be        molded with a 45-45 degree pattern, resulting in a more rigid        structure that would minimize buckling.    -   Brockwell Structures have the flexibility to address torsional        forces by using more than one type of weaving pattern. Also,        Brockwell Structures have the capability to add filler—by adding        a filler of rigid, high density foam, torsional resistance can        be enhanced.    -   To increase the tensile resistance, more carbon, Kevlar, or        Zylon could be added longitudinally into the skeletal structure        core (by molding). These elements can be pre-tensioned to        increase stiffness, thus reducing deflection of the Brockwell        Structures.

A significant difference between the mechanical properties of FRPs andmetals has been the difference between their behaviors under loads.Typically, FRPs exhibit brittle behavior as shown by their linearstress-strain relationships, whereas metals exhibit elastic-plasticbehavior as exhibited by their bilinear stress-strain relationships. Thesignificant increase in strain energy stored in the case of the bucklingbehavior of the Brockwell structure is obvious from FIGS. 3A-C whichshow its superiority over the catastrophic failure mode of the otherstructures.

Reference to the results shown in FIG. 9 will now made in made detail.Referring to FIG. 9, this figure shows two embodiments of the BrockwellStructure with embedded core, with and without a weave, as compared to anormalized high-quality carbon fiber tube in a bend test. The graphdepicts the normalized bending moment of specimens as compared toneutral axis curvature in order to establish a baseline for comparisonto existing high-performance building elements. As well, a simulatedcurve depicting the performance of aluminum with and without hardeningis added to the graph for further comparison. The graph reveals a linearstress-strain curve for the carbon-fiber tube, bilinear curves for theBrockwell Structures, as well as a bilinear curve for the aluminum.Carbon-fiber composites have historically exhibited a linearstress-strain curve, indicative of failure without warning. Metals,however, have historically exhibited a bilinear curve, which indicates ayielding prior to failure. In the Brockwell Structure, yielding isdemonstrated by the wave-like shape 13 acquired by the structure priorto skeletal failure. This may also be interpreted as a warning prior tocatastrophic failure. The Brockwell Structures mimic the bilinear curveof metals while maintaining a normalized bending rigidity on par withtubes of similar mass, as shown by comparing test 4 to number 16 and 1on the graph and in the corresponding illustrations.

The weaved sample has much higher buckling loads by restricting thebuckle to occur at higher frequencies via strain distribution by theanchored weave. The area under the curve represents the energyabsorption of the various specimens. Given the area under theweaved-specimen curve is greater than those of all other specimens, thiscorresponds to higher strength, impact tolerance, and energy absorptionthan other specimens, thus demonstrating the Brockwell Structure'ssuperior performance, bridging the gap between prior compositestructures and metals to elevate structural engineering potential andunderstanding.

Referring now to the results of FIG. 9 B, this simple histogramdemonstrates the reduced linear density of Brockwell Structures ascompared to tubes. This shows that the linear mass of the tube wasgreater than that of compared specimens with or without the weave.

Referring now to the results of FIG. 9 C, this shows that the bendingrigidity of the Brockwell Structures were on par with that of the tube.Though still lower than that of the tube, this may be interpreted as anadvantage, as rigidity corresponds to the brittle and violent modes offailure typical of current carbon-fiber building elements. As well,slightly reduced rigidity allows for visual identification of stressedmembers, as demonstrated in FIG. 9A.

Referring now to FIG. 9 D, this histogram visually represents therespective areas directly below each plotted line in FIG. 9A. As shown,energy absorption with the weaved specimen is nearly triple that of thetube's.

With regard to the results of FIGS. 10 A-10D, FIG. 10A shows bendingrigidity test results from samples tested, including test number,identification of sample type, and results. This is not normalized forlinear mass density. FIG. 10B shows comparative linear mass densities ofsamples tested, including test number, identification of sample type,and results. FIG. 10 C shows normalized bending rigidity across samplesanalyzed, including test number, identification of sample type, andresults. FIG. 10 D shows the normalized energy absorption across allanalyzed samples, including test number, identification of sample type,and results.

Reference will now be made to joints and methods for jointing theaforesaid structural members according to some embodiments. Thestructural members may be joined together in different ways usingdifferent types of joints. The jointed structures have very strongjoints due to a weave pattern of a tensile material that compresses inupon the joint structure, transferring load from one member to the next.Where stress is concentrated, resin or other materials such as rubberresist compression and distribute load across the member cores. By wayof example, referring to FIGS. 15 A to 15 E, there is depicted anexemplary jointed structure at different stages of formation accordingto one embodiment. Two or more of the aforementioned energy-absorbingstructural members are jointed together by joint components 15, 16, 17.

FIGS. 15 A to 15 E, illustrate formation of an elbow joint connection inwhich one end of one of the elongated skeleton structures is joined toan end of the another of the elongated skeleton structures. The joinedskeleton structure ends are cut such that they have complementaryprofiles. In the example of FIGS. 15 A to 15E the joining ends are cutat 45 degree angles so that the skeleton structures 2 can be framed intoa right angle. However, the complementary end profiles can be selectedto provide any jointing angle from 0 to 180 degrees. The structure endsare joined together with one or more grooves (v-profile groove(s) in theexamples) formed by adjacent strips of one end substantially alignedwith corresponding grooves formed by adjacent strips of the other end(see for example FIG. 15C). Weave 4 and/or notches 3 may be present atthe extremities of the structure ends being joined together or may beabsent therefrom as shown in FIGS. 15 A to E.

Joint component 14 is a joint compression resistant resin set into thejoint inside corner at the intersection formed by the aforementionedskeleton structure end grooves joining together. As best shown in FIG.15E, resin 14 sets to the shape of the intersecting joining grooves.Joint component 15 is a compression resistant member for fixedly seatingin and joining substantially aligned grooves together. The compressionresistant member is formed from carbon or other compression resistantmaterial and shaped to match the insider corner profile of the joininggrooves. For example, in FIGS. 15A to E, joint component 15 istriangular shaped to match the inside corner profile of the V groovesjoining at right angles. Component 15 is set in the inside corner of thejoint bridging joined aligned grooves of the skeleton structure ends.Component 15 can be secured by a suitable epoxy resin or may be setwithin joint compression resistant resin member 14. Joint compressionresistant resin member 14 may be utilized with or without component 15.

In one example, two of the skeleton structures are tacked together usingtwo triangular lateral reinforcing carbon fiber spars or members 16, oneon each side of the joint adhered to the skeleton in conjunction withcomponent 15 adhered to the interior aspect of the joint, embedded inthe compression-resistant resin base 14 as shown in FIGS. 15A to E.

With one or more of the joint components 14,15,16 adhered in place asdesired, a wrapping, or whipping 17, of Kevlar or other tensile materialis then added, both to compress the joint components together forstability, and to provide resistance from separation. In the example ofFIGS. 15A to E, the Kevlar is wrapped using a series of interwoven X's,building upon each other perpendicular to the plane of the cut in theskeletal beams. Additionally, a relief wind may be added from beam tobeam, overlapping with the tensioned weave 4 of the beam and the on bothsides of the joint. This serves to statically anchor the weave andstructural elements 2 together. A variety of different windings may beused to accommodate task-specific requirements. These joints may befabricated to accommodate any jointing angle, ranging from 0 degrees to180 degrees. To modify for variance in angle, the joint componenttriangular spars 15, 16 are cut to the same angle as the intended joint.In the figures shown, both members are cut at 45 degree angles andjoined such that their cumulative angle of intersection equals 90degrees.

FIGS. 15 F to 15 G illustrate different stages of construction of ajointed structure according to another embodiment. As shown in FIGS. 15Fto 15G, the jointed structure is a T joint in which one end theaforesaid skeleton structure is joined to the side of another of theskeleton structures. The structures are joined together using a quickjoint. The quick joint is a based on a captured nut 30 and bolt 31attachment system. To create the joint, high-strength plates 29 shapedto fit desired angles are bolted 31 into captured V-nuts 30 retained bythe tensioned weave. The V-profile of the nut fits into the V-shapedgroove 34 of the X-beam, thus preventing it from turning. For otherexamples in which the skeleton structure 2 has a different crosssection, the nut 30 is shaped to fit into the grooves according to theform and placement of the adjacent strips. This provides a secure andsimple platform for attachment to dissimilar structures or materials.Using this system, the Brockwell Structure may be easily used as ageneric framing structure system with simple attachments for fast andeasy assembly. In the figures shown, a structural member has beenattached to another section of a structural member, using a 90 degreeplate attachment 29 to form a T-junction. However, the quick jointplates can be configured to connect structural members in otherconfiguration such as Y joints, elbow joints etc. The angle at which thebeams intersect may be altered by changing the alignment angle of theholes and margins of the jointing plate 29. As well, the platesthemselves may be bent or curved.

FIG. 16 A illustrates a perspective top view of an exemplary U shapedlateral slide joint slidably mounted on the exterior of a skeletonstructure according to one embodiment. FIG. 16 B illustrates aperspective rear view of the exemplary lateral slide joint of FIG. 16 Adissociated from the skeletal structure. The skeleton structure on whichthe U shaped joint is slidably mounted is formed from strips 30 in thesame manner as for structural members of other embodiments but thestructure omits notches. No weave is carried on the skeleton. Astructure with notches but without weave is also envisaged.

Member 23 is U shaped member such that, when slidably engaged with thegroove, the member overlaps three exterior sides of the skeletonstructure. In the example of the slide joint of FIGS. 16A & B, aV-shaped groove engaging longitudinal nut or other member 21 is carriedon an inside side wall of a U member or chassis 23 for engaging, via oneend of the skeleton structure, the longitudinal V groove 34 of thestructure. In this manner, the U shaped chassis is slidably retained inthe V groove by the V shaped nut 21. Member 23 has holes on an exteriorside for mounting thereon other structures, devices etc. Additionally,the slide joint shows a friction-resistant jacket 22 that lines theinside walls of the U member 21 and is in contact with the sides of theskeleton structure when member 21 is slidably retained in the skeletonstructure groove.

FIGS. 18A to 18D illustrate different stages of construction of anexemplary T jointed structure connection according to one embodiment. Inorder to create a permanent T-joint, or to attach an aforesaidstructural member at 90 degrees to another of the structural members,the joining beam is cut at 45 degrees twice from opposite sides of thebeam, such that two 45 degrees cuts intersect at the center of the+-skeleton 33. By cutting away one face of the weave 4 on the spanningbeam, where the joint will intersect it, the point 33 of the joiningbeam may be inserted into the exposed v-profile 34, such that theprofiles of the skeletal strips of the two beams intersect, allowing fordistribution of load/stress through the proximal member cores 1. Byusing two internal 45 degree members spars 15, embedded in resin 14, oneon either side of the jointing beam, the angle of intersection isdefined, and the beam may then be compressively lashed 17 with lashingmaterial such as Kevlar or other tensile material to add tensionalresistance and to intersect with the adjacent weaves 4. As with the 90degree joint, the jointing weaving consists of a series ofstrain-distributing windings 17 which reinforce the skeletal spars 15,and distribute load across the skeletal cores 1. Wind techniques varyaccording to the application. For additional permanence, resin may beapplied to the winding to create a more static joint. Variance in jointangle may be accommodated by adjusting the angles of the resin-embeddedskeletal spars 15 with shaped joints 14 to complementary angles, as wellas adjusting the beam cut 33 to requirement, allowing for core proximityand strip intersection/contact.

In summary, the Brockwell structure provides a new generation oflightweight and high-strength building materials, having a highstrength-to-weight ratio and superior energy absorption and elasticitycharacteristics. The structural members have enhanced load bearingcapacity per unit mass which can be optimized for task-specific duties.The structural members may be configured to resist buckling, yet isdesigned to do so prior to failure. The structural members may provideincreased safety with structural energy absorption. The structuralmember may be configured for structural applications such as beams,cantilevers, supports, columns, spans, etc.

It is to be understood that the described embodiments of the inventionare illustrative only and that modifications thereof may occur to thoseskilled in the art. Accordingly, this invention is not to be regarded aslimited to the embodiments disclosed, but is to be limited only asdefined by the appended claims herein.

What is claimed is:
 1. An energy-absorbing structural member having anenhanced load bearing capacity per unit mass, the structural membercomprising: strips of a compression material formed into a skeleton ofdesired shape; spaced notches placed on side of the strips ofcompression material; and a tensile material which is woven around acentral axis of the skeleton in a desired weave and placed in thenotches.
 2. The structural member of claim 1 wherein the compressionmaterial is carbon fiber.
 3. The structural member of claim 1 whereinthe tensile material is aramid fibers.
 4. The structural member of claim1 further comprising an embedded core of internal strands of thermosetliquid crystalline polyoxazole.
 5. The structural member of claim 1wherein a pattern of the weave varies in accordance with the structuralneeds.
 6. The structural member of claim 1 further comprising a coatingover the structure.
 7. The structural member of claim 6 wherein thecoating is UV-resistant.
 8. The structural member of claim 6 wherein thecoating contains metal.
 9. The structural member of claim 1 wherein apattern of the weave is configured such that, when said structuralmember is broken in use, said weave keeps the broken structural membertethered together and total catastrophic failure is prevented.
 10. Anenergy-absorbing structural member having an enhanced load bearingcapacity per unit mass, the structural member comprising an elongatedskeleton structure comprising a plurality of strips of material; whereinsaid plurality of strips are joined together lengthwise along or arounda common central axis of said skeleton structure and have long distaledges spaced apart about said common central axis; and spaced notchesplaced on the strips of material for anchoring tensile material to bewoven around said common central axis of the skeleton structure in adesired weave.
 11. The member of claim 10, further comprising tensilematerial which is woven around said common central axis of the skeletonstructure in a desired weave and placed in the notches.
 12. The memberof claim 10, wherein said strips of material comprise strips of rigidelastic material.
 13. The member of claim 11, further comprising acentral core of tensile or flaccid material embedded in said skeletonstructure and extending along said common central axis such that, whenin use, propagation of a structural failure in said skeleton structureis resisted by said embedded tensile or flaccid material.
 14. The memberof claim 13, wherein said member is a multicomposite material structuralmember wherein the material of said strips, said embedded core and saidweave are selected to provide a multiple loading phase structuralmember.
 15. The member of claim 11, further comprising an embeddedcentral core comprising a tensile material.
 16. The member of claim 15,further comprising a binding agent adhering said weave to said notches.17. The member of claim 11, wherein said notches are spaced along saidstrip distal edges.
 18. The structural member of claim 17, wherein atensile or flaccid material is formed in said strips proximate saidnotches such that, when in use, propagation of a structural failure insaid notch is resisted by said tensile or flaccid material formed insaid strips for resisting propagation of notch failures.
 19. Thestructural member of claim 18, wherein said failure propagationresistant material comprises tensile material.
 20. The structural memberof claim 11, wherein said weave tensile material comprises aramidfibers.
 21. The structural member of claim 11, wherein said weavetensile material is pre-tensioned.
 22. The structural member of claim11, wherein said strips of material comprise strips of carbon fiber,glass or plastic.
 23. The structural member of claim 11, wherein saidskeleton structure has a cross section selected from a group of crosssections consisting of X shaped, +shaped, T shaped and Y shaped.